I've found a weird routing proposal:

• 1. http://map.project-osrm.org/?z=17&center=33.620985%2C-117.927557&loc=33.618595%2C-117.929901&loc=33.621101%2C-117.926458&hl=en&alt=0

The turn around and all turning instructions are allowed. But there is a better routing: simply to take the primary_link which allows to pass from CA 55 to CA 1.

Even more strange: it looks like he simply doesn't want to take the motorlink!

• 2. http://map.project-osrm.org/?z=18&center=33.621108%2C-117.928635&loc=33.620445%2C-117.929215&loc=33.621195%2C-117.927139&hl=en&alt=0
• 3. http://map.project-osrm.org/?z=18&center=33.621108%2C-117.928635&loc=33.620391%2C-117.929306&loc=33.621195%2C-117.927139&hl=en&alt=0

Hopefully this one looks ok:

• 4. http://map.project-osrm.org/?z=17&center=33.623138%2C-117.929306&loc=33.620453%2C-117.929183&loc=33.620985%2C-117.928571&hl=en&alt=0

I've looked at the OSM tags and everything looks ok. It has to be noticed that Mapzen has no issue to find this routing.

Any idea?